um: Remove usage of irq_chip->release()

UML does no longer need irq_chip->release().
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

arch/um/kernel/irq.c

@@ -334,7 +334,6 @@ static void dummy(struct irq_data *d)
 /* This is used for everything else than the timer. */
 static struct irq_chip normal_irq_type = {
 	.name = "SIGIO",
-	.release = free_irq_by_irq_and_dev,
 	.irq_disable = dummy,
 	.irq_enable = dummy,
 	.irq_ack = dummy,
@@ -342,7 +341,6 @@ static struct irq_chip normal_irq_type = {
 
 static struct irq_chip SIGVTALRM_irq_type = {
 	.name = "SIGVTALRM",
-	.release = free_irq_by_irq_and_dev,
 	.irq_disable = dummy,
 	.irq_enable = dummy,
 	.irq_ack = dummy,